A body part is known as roof spar for example from DE 198 58 903 A1 and serves for the partial reinforcement of the frame part in the region of pillars of the body of the motor vehicle. The structural component is designed as stiff mass and has a plurality of protrusions with which it supports itself on the inner wall of the roof spar. Positioning of the stiff mass takes place via humps supporting in the pillars. Furthermore, the stiff mass has depressions in the region of screw connections of the frame part. Fastening of a further component is thus exclusively performed on the frame part.
Disadvantageous with the known body part is that the structural component only brings about minor stiffening of the frame part since for example all forces of the component screwed to the body part are directly introduced into the frame part. In addition, the protrusions and the humps hinder coating of the roof spar in a dipping basin.